U.S. patent number 4,245,312 [Application Number 05/881,983] was granted by the patent office on 1981-01-13 for electronic fuel injection compensation.
This patent grant is currently assigned to The Bendix Corporation. Invention is credited to Didier J. deVulpillieres.
United States Patent |
4,245,312 |
deVulpillieres |
January 13, 1981 |
Electronic fuel injection compensation
Abstract
A method and apparatus for controlling the various functions of
an internal combustion engine using a program-controlled
microprocessor having a memory preprogrammed with various control
laws and associated control schedules receives information
concerning one or more engine-operating parameters such as manifold
pressure, throttle position, engine coolant temperature, air
temperature, engine speed or period and the like. These parameters
are measured and their values are supplied to input circuits for
signal conditioning and conversion into digital words usable by the
microprocessor. The microprocessor system computes a digital word
indicative of a computer-commanded engine control operation and
output circuitry responds to predetermined computer-generated
commands and to the computed digital command words for converting
them to corresponding pulse-width control signals for controlling
such engine operations as fuel-injection, ignition timing,
proportional and/or on-off EGR control, and the like. Various
techniques for modifying the basic fuel control laws stored in the
memory are provided for acceleration enrichment purposes and
look-up tables of such values stored in the memory may include any
number of break points or thresholds since a unity intercept
concept is used in the interpolation process to compute the
appropriate modifier value.
Inventors: |
deVulpillieres; Didier J.
(Southfield, MI) |
Assignee: |
The Bendix Corporation
(Southfield, MI)
|
Family
ID: |
25379640 |
Appl.
No.: |
05/881,983 |
Filed: |
February 27, 1978 |
Current U.S.
Class: |
701/110; 123/486;
701/108 |
Current CPC
Class: |
F02D
41/26 (20130101); F02D 41/2416 (20130101); F02D
41/10 (20130101); F02D 41/0047 (20130101) |
Current International
Class: |
F02D
21/00 (20060101); F02D 41/00 (20060101); F02D
41/26 (20060101); F02D 41/10 (20060101); F02D
21/08 (20060101); F02B 003/10 (); F02D 005/00 ();
F02M 007/06 () |
Field of
Search: |
;364/424,435,431
;123/32EA,32EH,32EB,32EC,117D,119EC,119R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gruber; Felix D.
Attorney, Agent or Firm: Haas, Jr.; Gaylord P. Wells; Russel
C.
Claims
I claim:
1. An electronic engine control system for controlling the supply
of fuel to an engine comprising means for measuring the time
interval between engine position pulses and computing a digital
number indicative of engine speed, computation means, memory means
for storing a program for implementing at least one fuel control
law, said program being executed by said computation means for
implementing said at least one fuel control law to normally compute
a primary fuel control pulse for controlling the supply of fuel to
said engine, means for detecting engine operating conditions
indicative of a need for acceleration enrichment and generating an
acceleration enrichment request signal, means responsive to said
acceleration enrichment request signal for addressing said memory
means with said stored digital number indicative of engine speed
for generating an acceleration enrichment modifier value signal
which is a function of engine speed, said computational means
executing said stored program for implementing said at least one
fuel control law and programmably modifying the normally-computed
primary fuel control pulse with said calculated acceleration
enrichment modifier value signal for generating an elongated,
acceleration enrichment-compensated primary fuel control pulse for
controlling the supply of fuel to said engine to maintain smooth
engine performance while avoiding "stumbling" and the like.
2. An electronic engine control system for normally generating a
primary fuel injection pulse for controlling the quantity of fuel
supplied to an engine including means for engine operating
conditions indicative of a need for acceleration enrichment and
generating an acceleration enrichment request signal in response
thereto, and means responsive to said acceleration enrichment
request signal for immediately generating an initial acceleration
enrichment fuel injection pulse if no normally-generated primary
fuel injection pulse is currently being outputted and delaying the
generation of said initial acceleration enrichment fuel injection
pulse whenever a normally-generated primary fuel injection pulse is
being generated until immediately after the normal termination of
said primary fuel injection pulse so that no portion of either said
normally-generated primary fuel injection pulse or said initial
acceleration enrichment fuel injection pulse is masked or lost
during the outputting of the other and the total quantity of fuel
supplied to said engine is sufficient to maintain smooth engine
operation even during conditions of acceleration.
3. A method of operating a microprocessor-based electronic engine
control system including a microprocessor means, memory means for
storing at least one look-up table of modifier values computed as a
function of at least one engine-operating parameter and program
means for implementing at least one control law, means for
measuring said at least one engine-operating parameter, said
microprocessor means being responsive to said at least one measured
engine-operating parameter for executing said program means for
implementing said at least one control law to compute a particular
engine control command, the method for addressing said look-up
table and computing an exact modifier value corresponding to the
actual measured value of said at least one engine-operating
parameter for use in implementing said at least one control law by
extending a straight line between pairs of addressed values below
the correction factor of one utilizing a "unity intercept"
technique to compute an overall correction factor compared to the
level of "one" law to compute said program-implemented engine
control command comprising the steps of:
(1) assigning a desired modifier value weight at a modifier value
Y.sub.1 for input address value X.sub.1 and a value of "ONE" for
the modifier value at a predetermined threshhold address level
X.sub.t ;
(2) extending a straight line from Y.sub.1, X.sub.1 to "ONE",
X.sub.t below the modifier value of "ONE";
(3) reading a Y.sub.2 modifier value (lower than ONE) at the
address value X.sub.2 ;
(4) interpolating between the modifier values Y.sub.1 and Y.sub.2
by linear interpolation techniques to compute an overall modifier
value corresponding to the actual measured value of
engine-operating parameter represented by the input address
variable X;
(5) comparing the computed overall modifier value Y to the value
ONE; and
(6) utilizing the greater of the computed modifier value Y and the
value ONE to modify said programmably-computed engine control
command thereby allowing any threshhold input value between the
addressed values X.sub.1 and X.sub.2 to be selected regardless of
the limited number of addressable locations for the variable input
values corresponding to measured values of engine-operating
parameters in the look-up table of modifier values stored in said
memory means.
4. An electronic engine control system for use with an internal
combustion engine system having an intake system, an exhaust
system, an engine block, a plurality of cylinders disposed in said
engine block, a piston operatively disposed within each of said
plurality of cylinders for reciprocal movement therein, means
responsive to fuel control signals for selectively supplying a
controlled quantity of fuel to a selected one or more of said
plurality of cylinders, the electronic engine control system
comprising computer means, memory means operatively coupled to said
computer means for storing data representative of at least one
look-up table containing a control surface of modifier values
computed as a function of engine speed, and program means for
implementing at least one fuel control law, means for measuring
engine speed and generating a signal indicative thereof, means for
temporarily storing said signal indicative of engine speed, said
computer means being responsive to said temporarily stored signal
indicative of engine speed for addressing said at least one look-up
table data of modifier values stored in said memory means and
generating a signal representative of a particular modifier value
corresponding to the actual measured value of engine speed
represented by said temporarily stored signal, said program means
utilizing said at least one fuel control law in response to said
computed particular modifier value for generating a modified fuel
control signal so that the controlled quantity of fuel supplied to
a selected one or more of said plurality of cylinders for ignition
purposes is a function of actual engine speed thereby maintaining
smooth engine performance and good drivability while avoiding
"stumble", "hesitation" and the like.
5. In an internal combustion engine system having computer means,
memory means associated with said computer means, program means
stored in said memory means for implementing at least one fuel
control law to compute a fuel control signal, preparing a look-up
table of modifier values which are a function of engine speed;
storing said look-up table of modifier values which are a function
of engine speed; storing said look-up table of modifier values in
said memory means; and means responsive to said fuel control signal
for controlling the quantity of fuel supplied to said engine, an
improved method of acceleration enrichment compensation comprising
the steps of:
measuring the speed of said engine to obtain a vaue indicative
thereof and generating a measured engine speed signal;
addressing the stored look-up table of modifier values with said
measured engine speed signal;
generating modifier value signals by interpolating between stored
modifier values to compute the particular modifier value
corresponding to said measured engine speed signal;
utilizing said program means including at least one fuel control
law to generate said fuel control signal; and
altering said at least one fuel control law by modifiying the fuel
control signal with said predetermined computed modifier value
signal corresponding to said measured engine speed signal to
generate a compensated fuel control signal corrected for
acceleration so as to maintain smooth engine performance and the
like.
6. In an internal combustion engine system including means
responsive to fuel control pulses for selectively controlling the
quantity of fuel supplied to said engine and engine control means
for normally computing primary fuel control pulses for operating
said fuel supply means, an improved method of acceleration
enrichment compensation comprising the steps of monitoring at least
one of throttle angle and manifold absolute pressure, detecting a
rapid change in said monitored one of said throttle angle and
manifold absolute pressure as an indication of a need for
acceleration enrichment, generating an extra additional one-time
acceleration enrichment fuel control pulse in response to said
detected need for acceleration enrichment, determining if the
generation of said extra additional one-time acceleration
enrichment fuel control pulse will occur during the normal
generation of said primary fuel control pulse and generating a
signal indicative thereof, immediately generating said extra
additional one-time acceleration enrichment fuel control pulse in
response to a signal indicating that said normally generated
primary fuel control pulse is not currently being generated, and
delaying the generation of said extra additional one-time
acceleration enrichment fuel control pulse until immediately after
the termination of said normally-generated primary fuel control
pulse in response to a determination that said primary fuel control
pulse is currently being generated for extending same to insure
that no portion of either of said fuel control pulses is masked or
lost and that said internal combustion engine receives sufficient
fuel even during acceleration periods to maintain smooth engine
performance and "drivability".
7. In an internal combustion engine having a control system for
normally generating main fuel control pulses and means responsive
to the duration of said fuel control pulses for selectively
controlling the quantity of fuel supplied to said engine for
combustion purposes, the improvement comprising acceleration
enrichment compensation means including:
means for monitoring at least one engine manifold absolute pressure
and throttle angle for detecting rapid changes therein;
means responsive to the detection of rapid changes in said
monitored at least one of manifold absolute pressure and throttle
angle for generating an acceleration enrichment enable signal
indicative of a need for acceleration enrichment;
means responsive to said acceleration enrichment enable signal for
normally generating a one-shot additional tip-in fuel control pulse
upon the leading edge of said acceleration enrichment enable signal
unless one of said normally-generated main fuel control pulses is
currently being generated and for otherwise generating said
one-shot additional Tip-In fuel control pulse immediately upon the
termination of said normally-generated main fuel control pulse for
effectively extending the pulse-width thereof; and
means for modifying said normally-generated main fuel control pulse
for longer term acceleration enrichment correction as a function of
engine speed, air temperature and the number of engine revolutions
elapsed since the generation of said acceleration enrichment enable
signal.
8. The improved internal combustion engine system of claim 7
wherein said engine control system includes computer means, memory
means operatively coupled to said computer means, program means
stored in said memory means for execution by said computer means to
implement at least one fuel control law, a first look-up table
containing a control surface of first acceleration enrichment
modifier values which are a function of engine speed, a second
look-up table containing a control surface of second acceleration
enrichment modifier values which are a function of air temperature,
and a third look-up table containing a control surface of third
acceleration enrichment modifier values which are a function of the
number of engine revolutions which have elapsed since the
generation of said acceleration enrichment enable signal, said
internal combustion engine system further including means for
measuring the actual speed of said engine and generating a RPM
signal indicative thereof, means for measuring the actual air
temperature and generating a TEMP signal indicative thereof, and
means for counting the number of engine revolutions elapsed since
the generation of said acceleration enrichment enable signal and
generating a DECAY signal indicative thereof, said means for
modifying said normally-generated fuel control pulses for longer
term acceleration enrichment correction including means for
performing a One Factoral Enrichment of said normally-computed main
fuel control pulse such that if T.sub.P (N) represents the
normally-computed main fuel pulse, T.sub.P(AE) represents the total
acceleration enrichment-compensated main fuel control pulse needed
to supply a sufficient quantity of fuel to said engine to maintain
smooth engine performance and good "dirvability" and "K" represents
the factoral enrichment factor, then T.sub.P(AE) =T.sub.P(N)
.times.(1+K), where K=K.sub.RPM .times.K.sub.AIR TEMP
.times.K.sub.DECAY where K.sub.RPM is said first acceleration
enrichment modifier value which is a function of engine speed and
which is determined by addressing said first look-up table with
said RPM signal and interpolating to compute the particular first
acceleration enrichment modifier value corresponding thereto, where
K .sub.AIR TEMP represents said second acceleration enrichment
modifier value which is a function of air temperature and which is
determined by addressing said second look-up table of acceleration
enrichment modifier values with said TEMP signal and interpolating
to calculate the particular acceleration enrichment modifier value
corresponding to the actual measured value thereof, and where
K.sub.DECAY represents said third acceleration enrichment modiifier
value which is determined from said third look-up table by
addressing said table with said DECAY signal and interpolating on
said control surface to calculate the particular third acceleration
enrichment modifier value corresponding to the actual number of
counts having elapsed since the generation of said acceleration
enrichment signal.
9. An acceleration enrichment system for use with an internal
combustion engine including means responsive to the measured values
of one or more engine-operating parameters for normally generating
primary fuel control signals and means responsive to the duration
of said fuel control signals for selectively controlling the
quantity of fuel supplied to said engine and therefore the
operation thereof, said acceleration enrichment system
including:
means for sensing engine-operating parameters and generating a
signal indicative of a need for acceleration enrichment including
generating an acceleration enrichment request signal in response
thereto;
means responsive to said acceleration enrichment request signal for
generating an immediate Tip-In acceleration enrichment fuel control
pulse if no main fuel control pulse if currently being generated
and for delaying the generation of said Tip-In acceleration
enrichment fuel control pulse until immediately after the
termination of said main fuel control pulse if said
normally-generated main fuel control pulse is currently being
generated; and
means responsive to said acceleration enrichment request for
additionally modifying said normally-generated main fuel control
pulse to effect a longer term, more gradual acceleration enrichment
correction so as to insure smooth engine performance and good
drivability.
10. The acceleration enrichment system of claim 9 wherein said
means for additionally modifying said normally-generated main fuel
control pulse to effect said longer-term more gradual acceleration
enrichment correction includes means for correcting said
normally-generated main fuel control pulse by multiplying same by a
One Factoral Factor (1+K) where "K" is a factor combining a first
acceleration enrichment modifier value which is a function of
engine speed, a second acceleration enrichment modifier value which
is a function of air temperature, and a third acceleration
enrichment modifier value which is a function of the number of
engine revolutions elapsed since the initiation of the present
acceleration enrichment sequence.
11. In an internal combustion engine system including means for
normally generating primary fuel control pulses and means
responsive to the duration of said fuel control pulses for
selectively controlling quantity of fuel supplied to said engine
for combustion purposes, an improved acceleration enrichment
compensation method comprising the steps of determining a need for
acceleration enrichment, generating an initial immediate Tip-In
fuel control pulse if no main fuel control pulse is presently being
generated and a delayed Tip-In fuel control pulse if a main fuel
control pulse is presently being generated, and modifying
subsequently generated main fuel control pulses with a long term
acceleration enrichment factor, said modifying said
normally-generated main fuel control pulses further including
computing a first acceleration enrichment multiplier value as a
function of engine speed, computing a second acceleration
enrichment multiplier value as a function of air temperature,
computing a third acceleration enrichment multiplier value as a
function of decay where decay represents the number of engine
revolutions having elapsed since the initiation of the current
acceleration enrichment sequence, multiplying said first, second
and third acceleration enrichment modifier values to obtain said
factor "K", and multiplying said normally-computed main fuel
control pulse by the quantity (1+K) to arrive at said
fully-acceleration-enrichment-compensated fuel control pulse for
achieving said long-term gradual compensation for the detected
acceleration.
Description
BACKGROUND OF THE INVENTION
1. Field Of The Invention
This invention relates generally to a method and apparatus for
controlling an internal combustion engine, and more particularly to
a microprocessor-based electronic engine control system having a
memory preprogrammed with various control laws and control
schedules responsive to one or more sensed engine-operating
parameters and generating signals for controlling fuel injection,
ignition timing, EGR control, and the like.
2. Statement Of The Prior Art
Many of the patents of the prior art recognize the need for
employing the enhanced accuracy of digital control systems for more
accurately controlling one or more functions of an internal
combustion engine.
U.S. Pat. No. 3,969,614 which issued to David F. Moyer, et al on
July 13, 1976 is typical of such systems as are U.S. Pat. No.
3,835,819 which issued to Robert L. Anderson, Jr. on Sept. 17,
1974; U.S. Pat. No. 3,904,856 which issued to Louis Monptit on
Sept. 9, 1975; and U.S. Pat. No. 3,906,207 which issued to
Jean-Pierre Rivere, et al on Sept. 16, 1975. All of these Patents
represent a break-away from the purely analog control systems of
the past, but neither the accuracy, reliability, or number of
functions controlled is sufficient to meet present day
requirements.
Future internal combustion engines will require that emissions be
tightly controlled due to ever-increasing governmental regulations,
while fuel consumption is minimized and drivability improved over
the entire operating range of the engine. None of the systems of
the prior art provide a method and apparatus for controlling the
operation of an internal combustion engine over even a portion of
its operating range with sufficient accuracy to attain minimal
emissions and minimal fuel consumption while simultaneously
obtaining improved drivability.
The systems of the prior art attempt to control one or more of the
engine-operating functions but none attempts to control the
operation of the fuel pump, fuel injection, engine ignition timing,
on-off and/or proportional EGR control, and the like while using
feedback from such devices as oxygen sensors for emission control
purposes or for effecting a closed loop fuel control mode of
operations, yet including provisions for optimizing acceleration
enrichment handling, and the like. Moreover, the systems of the
prior art are extremely expensive, difficult to repair and maintain
and are not commercially feasible at the present time.
These and other problems of the prior art are solved by the
microprocessor-based electronic engine control system of the
present invention which eliminates most or all of the problems of
the prior arts and enables a commercially feasible implementation
of a digital control system having a relatively low cost, and which
is easy to repair and maintain. The system of the present invention
is able to implement much more advanced and complex fuel control
laws and expand on the number of control functions performed
thereby to include the timing and duration of ignition, on-off
and/or proportional EGR control and the like while at the same time
reducing the cost and size of the unit and increasing reliability
so as to render the system commercially feasible.
These and other objects and advantages of the present invention
will be accomplished by the present method and apparatus for the
microprocessor-based electronic engine control of nearly all engine
functions over the entire operating range of the engine to minimize
engine emissions and fuel consumption while simultaneously
maintaining, if not improving, drivability and the like.
SUMMARY OF THE INVENTION
The method and apparatus of the present invention includes means
for detecting a need for acceleration enrichment and generating a
reliable initial acceleration enrichment pulse, commonly called a
Tip-In pulse, followed by an additional acceleration enrichment
amount determined at least partially as a function of engine speed
and the like to augment the main fuel pulse.
The additional acceleration enrichment amount is determined as a
One Factoral enrichment of the primary main fuel pulse T.sub.p (N)
computed for normal fuel injection purposes.
If T.sub.p (N) is the duration of the normal main or primary fuel
pulse, T.sub.p (AE) is the duration of the total fuel pulse after
an acceleration enrichment correction is factored in and "K" is the
factoral enrichment factor, then T.sub.p (AE)=T.sub.p
(N).times.(1+K).
The factoral enrichment factor "K" is a function of engine speed
(RPM), air temperature and a decay factor where the decay factor is
a modifier value addressed by the number of engine revolutions
which have elapsed since the initiation of the acceleration
enrichment enable sequence began. Therefore, K=K.sub.RPM +K.sub.AIR
TEMP +K.sub.DECAY.
The present system ensures that if the acceleration enrichment
Tip-In pulse is generated during the period of a
previously-computed mean or primary fuel pulse, then the Tip-In
pulse is delayed until the termination of the main fuel pulse and
then immediately added to prolong the period of the fuel pulse to
ensure that the one-time extra acceleration enrichment boost of
fuel is not masked or lost during the main fuel pulse. Otherwise,
the Tip-In pulse is immediately generated to provide an immediate
one-time additional boost of fuel to compensate for acceleration
enrichment.
A unity intercept concept is used for defining various breakpoints
in the required look-up table of values stored in the memory so as
to permit the use of a process for interpolating between two
address values X1 and X2 to compute an overall modifier value or
correction factor to be applied during fuel pulse calculation which
corresponds to the actual input variable X, and at the end of the
computed interpolation, the overall correction factor is compared
with a level of "one" and the highest of the two, i.e., the
computed correction factor or the value "1" is the only number used
as the table output correction factor or value for computation
purposes. With this approach, any threshhold level and any number
of breakpoints between successive addressable values X1, X2 may be
used regardless of limitations on the number of memory addresses
available.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 2 is a block diagram of the microprocessor-based electronic
engine control system.
INCORPORATION BY REFERENCE
This application is one of fourteen applications filed on Feb. 27,
1978, all commonly assigned and having substantially the same
specification and drawings, the fourteen applications being
identified below:
______________________________________ Serial Number Title
______________________________________ 881,321 Microprocessor-Based
Electronic Engine Control System 881,322 Feedback-Compensated
Ramp-Type Analog to Digital Converter 881,323 Input/Output
Electronic For Microprocessor-Based Engine Control System 881,324
Switching Control of Solenoid Current in Fuel Injection Systems
881,921 Dual Voltage Regulator With Low Voltage Shutdown 881,922
Oxygen Sensor Qualifier 881,923 Ratiometric Self-Correcting Single
Ramp Analog To Pulse Width Modulator 881,924 Microprocessor-Based
Engine Control System Acceleration Enrichment Control 881,925
Improvements in Microprocessor-Based Engine Control Systems 881,981
Oxygen Sensor Feedback Loop Digital Electronic Signal Integrator
for Internal Combustion Engine Control 881,982 Improvements in
Electronic Engine Controls System 881,983 Electronic Fuel Injection
Compensation 881,984 Ignition Limp Home Circuit For Electronic
Engine Control Systems 881,985 Oxygen Sensor Signal Conditioner
______________________________________
Application Ser. No. 881,321, has been printed in its entirety,
including FIGS. 1 to 10.34 and the specification of that
application is specifically incorporated by reference.
* * * * *